In 1995, I was asked to inventory bird species for
Fort Columbia State Park and the adjacent natural area by Brenda Senturia
of the Nature Conservancy. Fort Columbia is one of 3 retired army
installations on the Columbia River Estuary. The fort complex consists
of a single battery for large guns and about 10 houses (or barracks).
These are now open to the public. One has been outfitted as a youth
hostel. Behind the fort is a large (about 400 acre) woodland of mixed
Bigleaf Maple, Red Alder, Sitka Spruce, Western Hemlock and Douglas-fir.
I was asked to carry out monthly counts in the spring
and summer, a census in September and one in December for 1996 and 1997.
I also kept notes on other vertebrates I encountered and (with much less
rigor) blooming wildflowers.
Figure 1. A map of the study site including the numbered survey stations.
Method
I established 16 point-count stations at approximate
200 meters intervals beginning at the gate to the fort. These were
marked with orange surveyorís tapes (FigureÝ1). I made each count
in the morning (most within 2 hours of sunrise). During counts, I
looked and listened for 3Ýminutes, recording all birds seen or heard.
Because I had to walk back through all stations, I counted for an additional
minute on the return. Each survey took about 2 hours.
I did not count birds that were obviously outside
the park boundaries nor did I count random flyovers (this is why there
are no gulls or cormorants on the inventories). I selectively filtered
birds I felt overlapped stations. It may be assumed that all species
on the inventory represent birds using some part of the defined study site.
A list of bird species seen in adjacent estuarine areas, but not within
the study site may be found in appendix B-2.
Results
Table 1 shows the
total number of individuals seen of each species during each of the surveys.
Over the course of 13 visits 69 species were observed. Not surprisingly,
both number of individuals and number of species seen varied with time
of year (Figure 2 a & b), May and June being
the most productive periods of the year. 22 species can be categorized
as year round residents,18 as winter residents, 22 as summer residents
and 7Ýas migrants.
The presence of Hammondís Flycatcher (apparently
on territory) and Varied Thrush during the breeding season at an elevation
this low could be considered surprising. There is certainly plenty
of appropriate habitat for these species at Fort Columbia. The density
of woodpecker species is also noteworthy, especially the presence of territorial
Pileated Woodpeckers in consecutive years.
The fort area can be broken into 3 habitat types,
open/residential, mixed forest and coniferous. As one walks from
the main gate through the residences and up the fire road, this transition
is apparent. Figure 3 shows the relationship
between point station and number of species seen. Open/residential
and mixed forest appear to have a greater diversity of species associated
with them when compared to the denser coniferous forest habitats.
Discussion
Fort Columbia is a fairly typical coastal spruce/fir
forest community and the species encountered over the course of the inventory
reflect this habitat type. The fire road provides adequate, though
steep, access to the area. This road is vigorously maintained.
To some degree, this is understandable, if access as a fire road is still
necessary.
The road maintenance is, however, the one point about
which I feel obliged to express concern. It would appear that the
maintenance personnel are selectively targeting salmonberry along the roadside.
Rigorous salmonberry removal effectively manages wildlife away from
the trail edge, reducing the opportunities for viewing from the trail.
Salmonberry is an important early forage crop for birds and mammals, especially
hummingbirds. It creates edge habitat that increases diversity.
Salmonberry also provides an effective mechanism for keeping hikers from
wandering off the trail.
Salmonberry removal further provides an opportunity
for aggressive non-natives, like scotchbroom and Himalayan blackberry to
gain a foot hold. These non-natives are presently restricted to the
lower parts of fort. Early in 1997, a single individual with a gas
powered weed eater removed most of the salmonberry in the upper areas,
sometimes 15 to 2O meters on either side of the road, while leaving sword
fern and spruce trees. His efforts were almost certainly based on
either misidentification of the plant or a misplaced aesthetic rather than
fire road maintenance.
Any development plan for Fort Columbia should include
a well defined protocol for trail maintenance. Supervision of trail
maintenance personnel in regard to what species are removed and to what
limit beyond the road bed is essential, assuming one of the goals is management
for wildlife.
The road bed is very fragile. The thin layer
topsoil and organic debris is held in place by grasses and forbes.
This becomes saturated with water in the winter and spring. The machine
used for mowing the road has scarred several of the steeper portions.
This may be an unavoidable outcome of necessary maintenance, but points
to the need to restrict vehicles, including mountain bikes. Care
for the condition of the road bed would be another argument in favor of
keeping a healthy salmonberry edge along the road way, as well.
Conclusion
Fort Columbia can be considered a typical coastal spruce/fir habitat type with the expected bird species for Pacific Coast Range ecosystems. The residential and transitional zones within the Fort provide diversity without significantly impacting wildlife. It is recommended that road maintenance be restricted the minimum essential for fire suspression access and the visitor access be limited to foot traffic only.
